May 31, 2016, I had a chest CT because a 5 mm nodule was detected on an abdominal scan. This of course was just to get a better picture, but results showed three nodules, 5.5mm and 3mm lower left and a 3.8 lower right, pleural based. I didn’t think anything of it because I smoked for 18 years and my doctor explained that finding nodules is normal. (Haven’t smoked for 3 years, 41 yr old female.)

I followed protocol and returned for my six month scan last week. Apparently the 5.5 mm nodule in the left grew to 7mm and another “tiny”nodule was noted in the upper right lobe. They called the upper right stable, but it wasn’t noted previously so I’m guessing this may mean it’s not suspicious. The other nodules were not given a size, but were referred to as “tiny” and stable as well, I’ve not been given specifics despite my request for more information yet, but my doctor disconfirm that the larger nodule was not calcified. I have no information about the edges, the report just noted that benign and malignant eitiologies were present.

The notes also mentioned that the growth change couldn’t be verified due to size and may have been sliced differently (same machine, different radiologist reading results.)

My question is not whether I should wait to be rescanned (I will definitely follow up), but if there is such vagueness in the ability to measure, how would we even know when to be concerned? All of this began because I have chest pain that is diagnosed as costochondritis, a cough that’s hoarse, trouble swallowing (hypertrophic tonsils) and just feel not well. I’ve given up trying to find something to help and am not jumping to lung cancer at all, I just can’t understand if the measurements are even worth paying attention to.

It’s pretty standard to have a few mm difference in readings of CT scans. A study a few years ago showed that a group of radiologists read the same scan but gave differing dimensions by several mm. As I recall sometimes the same radiologist read the same scan but came up with a difference. The problem isn’t just difference in slices at a nodule but the edges are usually not an absolute so that a mm or 3 is an accepted difference.

Nodules that small don’t cause symptoms with the possible exception that they are growing into or pushing against another structure near the lung. So it’s extremely unlikely the nodules are causing any of your issues. Nodules less than a cm are normally followed for a while by scans to make sure they stay stable or if from infection, go away.

I hope you find relief from your symptoms and I hope your nodules stay put.

Just to add to Janine’s helpful information, I’d like to explain a little about how CT images “slice” or “cut”. The CT scanner takes a large number of images at very slightly different angles but because of those differences there can be visual data added or lost due to being at or near the spot where each of those images begin or end. The slightly changed angle alters the appearance of the nodule. Plus, on one scan where a nodule is centered in the image, it may appear larger than it might if it were on the edge. These are small differences (just take out a metric ruler and see how small 1.5mm is!) which really don’t tend to be significant. For larger changes, these issues become less important and the growth of a nodule is much easier to determine. Similar to if you weigh yourself on two different bathroom scales; if you were at 150 and each scale now reads 160, you can pretty much figure you’ve been snacking too much. But if an object weighs 10 ounces on one scale and 9.5 on another, that half ounce is most likely within the tolerance of the scale and does not represent a true difference.

All this is in addition to the issues of how a radiologist measures a non-circular nodule as Janine described.